Weird noise from the back end.

[MalcB]

I've had a strange noise from the back of the car for some while now. Seemed to start after having a Milltek cat back fitted. Sounds like rubbing or vibration against the underside and only happens' with engine braking at about 2000 rpm going down hill and when things have warmed up. It will stop if I disengage the clutch or press on the gas pedal. It is also more prevalent when I've got weight in the back. I've been underneath many times but can't see anything amiss. At one point I thought the exhaust was touching the ARB when it got hot...
Any idea's ....

 

[scotty dugg]

Very interested to see what this turns out to be, I've something almost identical, thought it might be the exhaust heat-shield vibrating off of the back-box.

Does yours sound like a rattle/whirring sort of noise? Can be heard inside the car and is quite loud outside?

 

[MalcB]

Very interested to see what this turns out to be, I've something almost identical, thought it might be the exhaust heat-shield vibrating off of the back-box.

Does yours sound like a rattle/whirring sort of noise? Can be heard inside the car and is quite loud outside?

Yes that's it exactly. Initially thought it was something rubbing on a tyre. Car is in to have a service and resonated box fitted
so I'll get them to have a look. I've been under the car many times undone the exhaust clamps in effort to realign. Put masking
tape on the ARB to see if it marked. Still no idea ...

 

[scotty dugg]

Yeah, I've had a few places look over the car and there's never been anything come up in regards to what could be the cause. the Heat shield seems pretty solid.

Maybe the exhaust will drown out the sound for a while

 

[MalcB]

Had it checked out properly today. Turns out it's the rear diff

 

[scotty dugg]

Had it checked out properly today. Turns out it's the rear diff

I was worried you'd say that! What's the damage?

 

[MalcB]

Don't know yet. Not cheap I suspect. Not only that. The steering rack needs changing as well. Thought I had the rattley rack syndrome. Bl@@dy cars. Having said that the S3 is probably the best all round car I've owned..........and I've had a few

 

[scotty dugg]

Don't know yet. Not cheap I suspect. Not only that. The steering rack needs changing as well. Thought I had the rattley rack syndrome. Bl@@dy cars. Having said that the S3 is probably the best all round car I've owned..........and I've had a few

I think the mk5 R32 diff is a straight swap? I know my list of things to fix is ever growing! Sorry to hear about the steering rack!

 

[MalcB]

Thanks I've got somebody on the look out for one. Read a few horror stories this morning about S3 diff's going pop

 

[scotty dugg]

Just heard someone else drive my car for me and the diff noise is a lot louder than I first thought!

Could someone confirm what diff I could replace mine with? Any 8P model? MkV R32 Diff?

 

[MalcB]

Just heard someone else drive my car for me and the diff noise is a lot louder than I first thought!

Could someone confirm what diff I could replace mine with? Any 8P model? MkV R32 Diff?

Up to June 2008 Part Number OAV525010B. There are variants after this ending in D or K but yes they use the same diff in the MKV R32 and A3 3.2.
I've just bought a diff for mine. However, having read a LOT of threads ....wheels bearings can also cause noise through the transmission. Mine's always been a bit strange as the noise is a lot more prominent when there are passengers in the back ?

 

[scotty dugg]

Up to June 2008 Part Number OAV525010B. There are variants after this ending in D or K but yes they use the same diff in the MKV R32 and A3 3.2.
I've just bought a diff for mine. However, having read a LOT of threads ....wheels bearings can also cause noise through the transmission. Mine's always been a bit strange as the noise is a lot more prominent when there are passengers in the back ?

How much did your diff end up costing? sent out a few requests, cheers for the info though I'll try a few more and see what they say.

It's sufficiently loud though, maybe I'll get it checked out when the clutch is changed.

 

[mephisto]

Ok i posted a thread about this a while back and just got mine back from the local garage with what i suspect is the same issue, i have a whirring noise from rear diff, which is especially audible on lift off from throttle, apply the throttle and it's somewhat quieter. Was informed not something they would touch.
Therefore i too am interested if you guys or anyone else out there could chip in on how i could source the parts, and how easy to replace? Would it be dropping out axle and removing both drive shafts?
I daren't take it to a stealer i just can't afford those costs at the moment

 

[MalcB]

There are various sources eBay, breakers etc. Prices range from £300 ish up to nearly a grand. I've been lucky in that I've sourced on here from a member. Won't get fitted until next month. I guess it's a job you could do yourself but Haldex will need a service as well. I've got a specialist sorting mine. Don't go to a main dealer they will try to charge £3K for a new one. Check your part number before buying.

 

[scotty dugg]

Every quote I've been given so far is for £500-550 delivered for a rear diff (I think some of them supply the haldex unit as well.

For changing it, struggled to find a guide so far, googling it brings up lots of oil change guides.

 

[MalcB]

The one I bought has Haldex controller and charge pump etc. Pretty heavy to do single handed on the drive I would think.
Looking at it I guess to remove you do the following
a ) Release drive shafts
b) Looks as though the ARB is in the way.
c) Undo prop shaft at Haldex coupling.
d) Disconnect Haldex connectors
e) Undo 4 retaining bolts and remove.

I'm sure somebody has done it on here and will be along with more ideas.

 

[mephisto]

Up to June 2008 Part Number OAV525010B. There are variants after this ending in D or K but yes they use the same diff in the MKV R32 and A3 3.2.
I've just bought a diff for mine. However, having read a LOT of threads ....wheels bearings can also cause noise through the transmission. Mine's always been a bit strange as the noise is a lot more prominent when there are passengers in the back ?

Cheers for info MalcB, mine is a 2009 S3 you say 'up to', does part number change for 09?
Ive had my local mechanic check mine and he was pretty sure it was drivetrain. It is a constant noise most prominent on lift off of throttle. esp around 20/30mph when there's little road noise, doesnt change if i swirve or corner hard. Are you changing your diff yourself?

 

[MalcB]

Cheers for info MalcB, mine is a 2009 S3 you say 'up to', does part number change for 09?
Ive had my local mechanic check mine and he was pretty sure it was drivetrain. It is a constant noise most prominent on lift off of throttle. esp around 20/30mph when there's little road noise, doesnt change if i swirve or corner hard. Are you changing your diff yourself?

Sounds very similar to mine. Part number OAV525010B seems to go up to June 2008. There are others ending in D or K but not sure which
yours will be. Not doing it myself. I've got a specialist garage on it. I've had enough of crawling around under cars over the years .
I should think it's possible DIY but quite a weighty thing do deal with on your drive.

 

[scotty dugg]

Just a heads up guys ( @MalcB ) , recenlty changed my diff oil and haldex oil/filter as well as disabling the exhaust flap.

Noise from the back seems to have disappeared.

Guide on flap disable: http://www.audi-sport.net/xf/threads/how-to-s3-exhaust-flap-mod.64998/

May be worth a try as well, not sure what fixed it but the exhaust flap was almost seized so I'd hazard a guess it could be that, worth a shot!

 

[MalcB]

Just a heads up guys ( @MalcB ) , recenlty changed my diff oil and haldex oil/filter as well as disabling the exhaust flap.

Noise from the back seems to have disappeared.

Guide on flap disable: http://www.audi-sport.net/xf/threads/how-to-s3-exhaust-flap-mod.64998/

May be worth a try as well, not sure what fixed it but the exhaust flap was almost seized so I'd hazard a guess it could be that, worth a shot!

Thanks but I got a Milltek cat back system. You were fortunate by the sound of it. My diff was replaced on Friday apparently it was pretty rough.
Not got the car back yet as I'm having the steering rack done as well (New Bosch unit) but the required loom for the later series rack
is currently out of stock. So Tom at Retro Resus who's doing the job for me is shopping around at the moment to find one.

 

[scotty dugg]

Thanks but I got a Milltek cat back system. You were fortunate by the sound of it. My diff was replaced on Friday apparently it was pretty rough.
Not got the car back yet as I'm having the steering rack done as well (New Bosch unit) but the required loom for the later series rack
is currently out of stock. So Tom at Retro Resus who's doing the job for me is shopping around at the moment to find one.

Ah not so good then, hopefully that'll fix it. I was going to straight through the exhaust if it wasn't resolved soon!

 

[MalcB]

All sorted. Replacement diff fitted, replaced all transmission oils and fitted a new steering rack. Feels like a new car again. No rattles and grinding noises. I can highly recommend RetroResus in Bridgwater. A new business run by Tom Walker. Top man.

 

[mephisto]

Just a heads up guys ( @MalcB ) , recenlty changed my diff oil and haldex oil/filter as well as disabling the exhaust flap.

Noise from the back seems to have disappeared.

Guide on flap disable: http://www.audi-sport.net/xf/threads/how-to-s3-exhaust-flap-mod.64998/

May be worth a try as well, not sure what fixed it but the exhaust flap was almost seized so I'd hazard a guess it could be that, worth a shot!

Thanks for the update Scotty that's great news!

Can you or anyone here confirm this sounded like your noise, i have recorded mine you can hear the noise on throttle lift off, any comments welcome.

Below link is to an mp3 i recorded in my car few days back. Nothing dodgy i assure you!

http://goo.gl/ewh7fN

 

[MalcB]

Ouch! Sorry but that sounded like mine did which resulted in a diff change.
Sound changes with road speed on lift off. Sounds a bit like a tyre rubbing on something at the rear.
Oddly mine sounded worse when I had weight in the back.
Good luck I hope you can sort it..

 

[scotty dugg]

Just had a listen, sounds different to what I had, it was more of a rattle than a drone. Looks like @MalcB has diagnosed it.

Exhaust and intake sound good though.

 

[MalcB]

If you have to get another diff check the part number on your casing. I bought pt no OAV525010B (all indictations showed this as correct) but had to change the Haldex unit over to my original. The actual part number on my dodgy diff one was OAV525010K.